Perpectual Motion

Re: Perpectual Motion


I have seen three very different mathematical proofs against perpetual motion. I'm not going to try to recreate them here, suffice to say that triple integrals play an important part in one version.

The real problem with perpetual motion is friction. There is no known way to support something in motion that does not also require energy to overcome sliding friction or viscous friction.

Another point, is that some folks do define perpetual motion as somehow able to supply energy to some other system, but that would be taking energy from the moving system, and thus bring it to a halt more rapidly. This goes back to Newton, you don't need Einstein's formulas to trash this idea.

Electric cars are a whole different animal. That is the state of the art in chemistry. For an electric car to be feasible you have to carry sufficient energy to travel fast enough and far enough to make things worthwhile. Having enough room to carry the family comfortably would be nice also. Then we want to be able to refill the system with energy, quickly, so we can keep going.

Hydrocarbon systems today provide the power, speed, range, and relatively rapid recharge rates we like. Unless you're in Florida sitting in line to get more gas.

Electric batteries today are very heavy, reducing performance. They have limited capacity for storing and delivering power, restricting range. And they take very much longer to recharge than is required to fill the gas tank, on the order of four to thirty six hours for two hours of run time depending upon speed.

One alternative to this is having fast swappable batteries. But then every vehicle maker must agree on a size, connector, and handling system to enable you to pull into a battery exchange shop where the battery would be removed by some device, think crane or forklift, a charged battery put in, and you're on your way. Even that is going to probably be an hour.

I investigated acquiring an electric motor cycle with a battery trailer from an outfit in California. Trouble is they couldn't deliver the range I had to have at the time. I figured I would just plug into my employer's outlet to charge the trailer and bike, and have three trailers. One at home charging, one at work charging, and one in use. That would have been necessary because the hour plus required to get to work would have required twelve hours to recharge the trailer batteries, and I didn't want to stay at work that long.

Hope this helps,
Kelly

Awesome thanks... but why isperpectual motion such a highly debated topic? I mean I know if and when it is figured out that it will used, but for what?

The debate probably stems from the fact that there are people who refuse to believe that it is impossible.

But if created do you not think that it will be covered up? like everyone says oil companies are trying to do with electrical cars?

If perpetual motion is created, then <fill in conclusion>.

Since the hypothesis is false, this statement is true no matter what conclusion you choose.

Therefore, "if perpetual motion is created, it will be covered up" is a true statement.

However, "if perpetual motion is created, it will not be covered up" is also a true statement.

this is true, but do you think that with the creation of perpectual motion that there will be "battle" over oil industry barrons and those who wish to make perpectual motion an energy source that could be used for travel? Eh i dont know where im going with this... all i know is have this conspriacy minded theory shooting through my mind and no one around here to talk it out with... sorryfor rambling on and on about it... but for some reason perpectual motion has just been stuck in my mind for some reason....

Re: Perpectual Motion


I think people associate perpetual motion with perpetual energy, or some type of unlimited energy source, which is why it has endured as a fantasy of wealth. Also, I think the human psyche is somehow entranced by complex physical movements such that rational understanding and mathematics and physics are discounted in favor of the "I just know it'll work" *feeling* that many people have.

The bottom line however is that you can't get something for nothing, and even though you can have perpetual motion, you cannot extract any energy from a perpetual system without disrupting that system.

Our Planet has been in orbit around our Sun for over 4billion years, and the same is true of countless other orbital systems, all of which are essentially perpetual motion systems (not exactly perpetual because there is *some* small bit of friction, and they will eventually slow down, but they are essentially perpetual). However, there is no energy being extracted from the system. So even though our planet has been in motion relative to the Sun for an unbelievable stretch of time, it is simply a system in motion, nothing magical is happening; we are not getting anything for nothing.

first of all, it's perpetual motion, not perpectual



a perpetual motion machine would still give off energy, because all things in motion will give off some energy. so if it was giving off energy and was still in perpetual motion, then this energy could be harnessed without stopping the perpetual motion.



I think that harnessing wind energy is a form of harnessing energy from the Earth's rotation. And solar panels allow us to harness energy from the sun. renewable resources like these are good enough to be perpetual for our purpouses.

the only practical purposes for a perpetual motion machine would be one that was compact enough to be used in mobile electronics and that provided more energy than solar or induction

[/quote]I think that harnessing wind energy is a form of harnessing energy from the Earth's rotation. And solar panels allow us to harness energy from the sun. renewable resources like these are good enough to be perpetual for our purpouses.[/quote]

Good enough? or just an easy answer to the question at hand? meaning that it would be to hard to come up with a perpetual motion machine? Cus if you think about wind energy, then what about windmills? wouldnt you have to have a material that was thin to be moved by the slightest winds but tough enough not to be broken by the strongest wind storms?

[/quote]the only practical purposes for a perpetual motion machine would be one that was compact enough to be used in mobile electronics and that provided more energy than solar or induction[/quote]

do you not think that the armed forces would have interest in perpetual motion?

my quotes didnt work

No it woulldn't. If it gave off energy, then it would eventually run down, and it wouldn't be perpetual motion by definition.



Wind energy is really solar energy, it has nothing to do with Earth's rotation.

I'm talking about perpetual motion as a theoretical concept which is perfectly closed and endless.

If you are talking about "virtually" perpetual systems such as orbital systems, or solar power systems, then it's a whole different question. We can run something with solar power for a very long time because the Sun will last a very long time, but it's not perpetual because the Sun is burning fuel, and will eventually run out.

I thought the original question in this thread was asking about the theoretic concept of perpetual motion, and why it was impossible. If we are now talking about extremely long duration motion, then that's different.

You need to close each quote with a [/quote] marker.

A slight correction.

Wind energy is actually harnessing energy from the Sun. The sun heats up parts of the Earth more than others creating air pressure to change and air to move from one place to another (this is over-simplified but basically correct). The energy comes from heat which is from the Sun.

The energy does not come from the rotation of the Earth. If it did, the speed of the Earth's rotation would slow rapidly.

Nice try, markr

There's a branch of science that covers converting energy from one form into another called Thermodynamics. In this study the term "entropy" (the symbol used is the letter "s") is defined. Any time you do anything involving energy, entropy comes along and takes a little bit away from you. Think of it as doing a lot of trading with your stockbroker - at every transaction a little of your money is lost to brokerage fees. Only with entropy, every time you do something with energy, some useful energy is forever lost as waste heat.

Thermodynamics has three basic Laws. A wiseacre back at school translated these into plain English as:

1. You can't win.
2. You can't break even.
3. You can't quit the game.

Perpetual motion isn't possible. Thermodynamics doesn't allow it.

The issue of perpetual motion is a very interesting topic in physics and in history. It became a bit issue the late 19th cetury study of thermodynamics which was spurred by the advent of steam engines.

There are actually two type of perpetual motion that have been proposed. As people have pointed out here, both are considered impossible since they each would break basic laws of physics.

The first type is the easiest to disprove. In this type you have a perpetual process that no only goes on forever, but you can continually take energy from the process and it will not slow down.

This breaks a very basic law of science-- "Energy can not be created or destroyed". Every time you do something that does work, the energy you use has to come from somewhere. After you do this work, the energy has to go somewhere.

For example, if I use 24 Joules of energy to lift a box, I must get that energy from somewhere. Fortunately I had a good breakfast this morning that has this energy. But where did the energy ultimately come from? Well my breakfast was made of wheat that grew in the Sun for a lot of time. So the energy came from the Sun.

Furthermore the energy from the sun comes from a nuclear reaction that will ultimately (in 5 billion years or so) burn out. So there is no infinite energy.

Incidently after I lift this box, the energy does not disappear. It is now stored in the box (as potential energy) and heat. The energy can not be destroyed.

So any time something happens you need to ask -- where did the energy come from? and where did the energy go?

In an alleged perpetual motion machine (of the first type) there is energy that was "created" (i.e. it didn't come from anywhere). This breaks the law and this is why we physicists are quite sure that it is impossible.

We have a slightly more complicated reason for knowing that the second form of perputual motion (where the motion goes forever, but no energy is removed) is also impossible. I would be happy to go on if there is any interest.

no...all systems give off energy, therefore if the system is not running down, then it MUST be creating energy from nothing...which as we know is impossible. but you are the one that said "if it's possible, then"



I was trying to make the point that a perpetual motion machine would not be very useful, because we already have plenty of renewable energy sources. I was trying to show that a perpetual motion machine would ONLY be useful if it was capable of powering devices in a small package and providing more than solar or some other renewable resource.